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Rehhagen C, Argüello Cordero MA, Kamounah FS, Deneva V, Angelov I, Krupp M, Svenningsen SRW, Pittelkow M, Lochbrunner S, Antonov L. Reversible Switching Based on Truly Intramolecular Long-Range Proton Transfer─Turning the Theoretical Concept into Experimental Reality. J Am Chem Soc 2024; 146:2043-2053. [PMID: 38214997 DOI: 10.1021/jacs.3c10789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2024]
Abstract
Herein, we demonstrate a working prototype of a conjugated proton crane, a reversible tautomeric switching molecule in which truly intramolecular long-range proton transfer occurs in solution at room temperature. The system consists of a benzothiazole rotor attached to a 7-hydroxy quinoline stator. According to the experimental and theoretical results, the OH proton is delivered under irradiation to the quinolyl nitrogen atom through a series of consecutive proton transfer and twisting steps. The use of a rigid rotor prevents undesired side processes that decrease the switching performance in previously described proton cranes and provides an unprecedented switching efficiency and fatigue resistance. The newly designed system confirms the theoretical concept for the application of proton transfer-initiated intramolecular twisting as the switching mechanism, developed more than 10 years ago, and provides unique insights for the further development of tautomeric molecular switches and motors, molecular logic gates, and new molecular-level energy storage systems.
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Affiliation(s)
- Chris Rehhagen
- Institute for Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany
| | - Miguel A Argüello Cordero
- Institute for Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany
| | - Fadhil S Kamounah
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
| | - Vera Deneva
- Institute of Electronics, Bulgarian Academy of Sciences, BG-1784 Sofia, Bulgaria
| | - Ivan Angelov
- Institute of Electronics, Bulgarian Academy of Sciences, BG-1784 Sofia, Bulgaria
| | - Marvin Krupp
- Institute for Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany
| | - So Ren W Svenningsen
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
| | - Michael Pittelkow
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark
| | - Stefan Lochbrunner
- Institute for Physics and Department of Life, Light and Matter, University of Rostock, 18051 Rostock, Germany
| | - Liudmil Antonov
- Institute of Electronics, Bulgarian Academy of Sciences, BG-1784 Sofia, Bulgaria
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Dobrikov GM, Nikolova Y, Slavchev I, Dangalov M, Deneva V, Antonov L, Vassilev NG. Structure and Conformational Mobility of OLED-Relevant 1,3,5-Triazine Derivatives. Molecules 2023; 28:molecules28031248. [PMID: 36770913 PMCID: PMC9921695 DOI: 10.3390/molecules28031248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 01/24/2023] [Accepted: 01/25/2023] [Indexed: 01/31/2023] Open
Abstract
A series of OLED-relevant compounds, consisting of 1,3,5-triazine core linked to various aromatic arms by amino group, has been synthesized and characterized. The studied compounds exist in solution as a mixture of two conformers, a symmetric propeller and asymmetric conformer, in which one of the aromatic arms is rotated around the C-N bond. At temperatures below -40 °C, the VT NMR spectra in DMF-d7 are in a slow exchange regime, and the signals of two conformers can be elucidated. At temperatures above 100 °C, the VT NMR spectra in DMSO-d6 are in a fast exchange regime, and the averaged spectra can be measured. The ratio of symmetric and asymmetric conformers in DMF-d7 varies from 14:86 to 50:50 depending on the substituents. The rotational barriers of symmetric and asymmetric conformers in DMF-d7 were measured for all compounds and are in the interval from 11.7 to 14.7 kcal/mol. The ground-state energy landscapes of the studied compounds, obtained by DFT calculations, show good agreement with the experimental rotational barriers. The DFT calculations reveal that the observed chemical exchange occurs by the rotation around the C(1,3,5-triazine)-N bond. Although some of the compounds are potentially tautomeric, the measured absorption and emission spectra do not indicate proton transfer neither in the ground nor in the excited state.
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Affiliation(s)
- Georgi M. Dobrikov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 9, 1113 Sofia, Bulgaria
| | - Yana Nikolova
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 9, 1113 Sofia, Bulgaria
| | - Ivaylo Slavchev
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 9, 1113 Sofia, Bulgaria
| | - Miroslav Dangalov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 9, 1113 Sofia, Bulgaria
| | - Vera Deneva
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 9, 1113 Sofia, Bulgaria
- Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
| | - Liudmil Antonov
- Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
| | - Nikolay G. Vassilev
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl. 9, 1113 Sofia, Bulgaria
- Correspondence:
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Deneva V, Slavova S, Kumanova A, Vassilev N, Nedeltcheva-Antonova D, Antonov L. Favipiravir-Tautomeric and Complexation Properties in Solution. Pharmaceuticals (Basel) 2022; 16:ph16010045. [PMID: 36678542 PMCID: PMC9864296 DOI: 10.3390/ph16010045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 12/16/2022] [Accepted: 12/23/2022] [Indexed: 12/31/2022] Open
Abstract
The tautomeric properties of favipiravir were investigated experimentally for the first time by using molecular spectroscopy (UV-Vis absorption, fluorescence and NMR), as well as DFT quantum-chemical calculations. According to the obtained results, the enol tautomer is substantially more stable in most of the organic solvents. In the presence of water, a keto form appears to be favored due to the specific solute-solvent interactions. Upon the addition of alkaline-earth-metal ions, deprotonation and complexation occurred simultaneously, giving the formation of 2 : 1 ligand : metal complexes. According to the theoretical simulations, the metal ion is captured between the carbonyl groups as a result of the size-fit effect.
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Affiliation(s)
- Vera Deneva
- Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
- Correspondence: (V.D.); (L.A.)
| | - Sofia Slavova
- Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
- Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Alina Kumanova
- Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
| | - Nikolay Vassilev
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Daniela Nedeltcheva-Antonova
- Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Luidmil Antonov
- Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria
- Correspondence: (V.D.); (L.A.)
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Georgiev A, Deneva V, Yordanov D, Völzer T, Wolter S, Fennel F, Lochbrunner S, Antonov L. Benzothiazol picolin/isonicotinamides molecular switches: Expectations and reality. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2022.118968] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Georgiev A, Yordanov D, Vassilev N, Deneva V, Nedeltcheva D, Angelov I, Antonov L. A single isomer rotary switch demonstrating anti-Kasha behaviour: Does acidity function matter? Phys Chem Chem Phys 2021; 23:13760-13767. [PMID: 34132295 DOI: 10.1039/d1cp01378e] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
A novel rotary switch, overcoming the disadvantages of hydrazone based switches with competitive proton acceptor sub-rotors, has been designed. The new compound contains a pyridyl ring and a COOH group as sub-rotors, which provides engagement of the pyridyl nitrogen atom and leads to the existence of a single isomer in the ground state. The availability of acidic functionality in the rotor creates conditions for excited state intramolecular proton transfer (ESIPT), which exhibits anti-Kasha behavior.
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Affiliation(s)
- Anton Georgiev
- Department of Organic Chemistry, University of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria
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Yordanov D, Deneva V, Georgiev A, Crochet A, Fromm KM, Antonov L. Indirect solvent assisted tautomerism in 4-substituted phthalimide 2-hydroxy-Schiff bases. Spectrochim Acta A Mol Biomol Spectrosc 2020; 237:118416. [PMID: 32388169 DOI: 10.1016/j.saa.2020.118416] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2020] [Revised: 04/21/2020] [Accepted: 04/25/2020] [Indexed: 06/11/2023]
Abstract
The paper presents the synthesis and characterization of two 4-substituted phthalimide 2-hydroxy-Schiff bases containing salicylic (4) and 2-hydroxy-1-naphthyl (5) moieties. The structural differences of 2-hydroxyaryl substituents, resulting in different enol/keto tautomeric behaviour, depending on the solvent environment were studied by absorption UV-Vis spectroscopy. Compound 5 is characterized by a solvent-dependent tautomeric equilibrium (KT in toluene = 0.12, acetonitrile = 0.22 and MeOH = 0.63) while no tautomerism is observed in 4. Ground state theoretical DFT calculations by using continuum solvation in MeOH indicate an energy barrier between enol/keto tautomer 5.6 kcal mol-1 of 4 and 0.63 kcal mol-1 of 5, which confirms the experimentally observed impossibility of the tautomeric equilibrium in the former. The experimentally observed specific solvent effect in methanol is modeled via explicit solvation. The excited state intramolecular proton transfer (ESIPT) was investigated by steady state fluorescence spectroscopy. Both compounds show a high rate of photoconversion to keto tautomers hence keto emissions with large Stokes shifts in five alcohols (MeOH, EtOH, 1-propanol, 1-butanol, and 1-pentanol) and various aprotic solvents (toluene, dichlormethane, acetone, AcCN). According to the excited state TDDFT calculations using implicit solvation in MeOH, it was found that enol tautomers of 4 and 5 are higher in energy compared to the keto ones, which explains the origin of the experimentally observed keto form emission.
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Affiliation(s)
- Dancho Yordanov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Vera Deneva
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Anton Georgiev
- Department of Organic Chemistry, University of Chemical Technology and Metallurgy, 1756 Sofia, Bulgaria; Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
| | - Aurelien Crochet
- Department of Chemistry and Fribourg Center for Nanomaterials FriMat, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Katharina M Fromm
- Department of Chemistry and Fribourg Center for Nanomaterials FriMat, University of Fribourg, CH-1700 Fribourg, Switzerland
| | - Liudmil Antonov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria; Institute of Electronics, Bulgarian Academy of Sciences, 1784 Sofia, Bulgaria.
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Solea AB, Cornu I, Deneva V, Crochet A, Fromm KM, Antonov L, Allemann C, Mamula O. Tautomerism and Self-Association in the Solution of New Pinene-Bipyridine and Pinene-Phenanthroline Derivatives. Molecules 2020; 25:E298. [PMID: 31940835 PMCID: PMC7024227 DOI: 10.3390/molecules25020298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/16/2019] [Accepted: 12/27/2019] [Indexed: 11/16/2022] Open
Abstract
Two novel pinene-type ligands have been synthesized and their tautomeric and self-associating behavior studied in solution and in the solid state. The first ligand, an acetylated derivative of 5,6-pinene-bipyridine, displays keto-enol tautomerism in solution. This tautomeric equilibrium was studied by NMR and UV-Vis spectroscopy in various solvents, and the results were compared with the ones obtained through DFT calculations. The second ligand was obtained by an unusual oxidation of the phenanthroline unit of a pinene-phenanthroline derivative. This compound exists as a single tautomer in solution and aggregates both in solution (as observed by NMR) and in the solid state through H-bonding as observed by X-ray structure determination and confirmed by DFT studies.
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Affiliation(s)
- Atena B. Solea
- Haute Ecole d’Ingénierie et d’Architecture Fribourg, HES-SO University of Applied Sciences of Western Switzerland, Pérolles 80, CH-1705 Fribourg, Switzerland; (A.B.S.); (I.C.); (A.C.); (C.A.)
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland;
| | - Ivan Cornu
- Haute Ecole d’Ingénierie et d’Architecture Fribourg, HES-SO University of Applied Sciences of Western Switzerland, Pérolles 80, CH-1705 Fribourg, Switzerland; (A.B.S.); (I.C.); (A.C.); (C.A.)
| | - Vera Deneva
- Bulgarian Academy of Sciences, Institute of Organic Chemistry with Centre of Phytochemistry, Acad. G. Bonchev street, bl. 9, 1113 Sofia, Bulgaria; (V.D.); (L.A.)
| | - Aurelien Crochet
- Haute Ecole d’Ingénierie et d’Architecture Fribourg, HES-SO University of Applied Sciences of Western Switzerland, Pérolles 80, CH-1705 Fribourg, Switzerland; (A.B.S.); (I.C.); (A.C.); (C.A.)
| | - Katharina M. Fromm
- Department of Chemistry, University of Fribourg, Chemin du Musée 9, CH-1700 Fribourg, Switzerland;
| | - Liudmil Antonov
- Bulgarian Academy of Sciences, Institute of Organic Chemistry with Centre of Phytochemistry, Acad. G. Bonchev street, bl. 9, 1113 Sofia, Bulgaria; (V.D.); (L.A.)
| | - Christophe Allemann
- Haute Ecole d’Ingénierie et d’Architecture Fribourg, HES-SO University of Applied Sciences of Western Switzerland, Pérolles 80, CH-1705 Fribourg, Switzerland; (A.B.S.); (I.C.); (A.C.); (C.A.)
| | - Olimpia Mamula
- Haute Ecole d’Ingénierie et d’Architecture Fribourg, HES-SO University of Applied Sciences of Western Switzerland, Pérolles 80, CH-1705 Fribourg, Switzerland; (A.B.S.); (I.C.); (A.C.); (C.A.)
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Deneva V, Bakardzhiyski I, Bambalov K, Antonova D, Tsobanova D, Bambalov V, Cozzolino D, Antonov L. Using Raman Spectroscopy as a Fast Tool to Classify and Analyze Bulgarian Wines-A Feasibility Study. Molecules 2019; 25:molecules25010170. [PMID: 31906182 PMCID: PMC6982931 DOI: 10.3390/molecules25010170] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Revised: 12/28/2019] [Accepted: 12/29/2019] [Indexed: 11/16/2022] Open
Abstract
Raman spectroscopy, being able to provide rich information about the chemical composition of the sample, is gaining an increasing interest in the applications of food. Raman spectroscopy was used to analyze a set of wine samples (red and white) sourced from rarely studied traditional Bulgarian wines. One of the objectives of this study was to attempt the fast classification of Bulgarian wines according to variety and geographic origin. In addition, calibration models between phenolic compounds and Raman spectroscopy were developed using partial least squares (PLS) regression using cross-validation. Good calibration statistics were obtained for total phenolic compounds (by the Folin–Ciocalteu method) and total phenolic compounds and phenolic acids (spectrophotometrically at 280 nm) where the coefficient of determination (R2) and the standard error in the cross-validation (SECV) were 0.81 (474.2 mg/dm3 gallic acid), 0.87 (526.6 mg/dm3 catechin equivalents), and 0.81 (44.8 mg/dm3 caffeic equivalents), respectively. This study has demonstrated that Raman spectroscopy can be suitable for measuring phenolic compounds in both red and white wines.
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Affiliation(s)
- Vera Deneva
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bldg. 9, 1113 Sofia, Bulgaria; (V.D.); (D.A.); (L.A.)
| | - Ivan Bakardzhiyski
- Department of Technology of Wine and Beer, University of Food Technologies Plovdiv, 26 Maritza blvd., 4002 Plovdiv, Bulgaria; (I.B.); (K.B.); (D.T.)
| | - Krasimir Bambalov
- Department of Technology of Wine and Beer, University of Food Technologies Plovdiv, 26 Maritza blvd., 4002 Plovdiv, Bulgaria; (I.B.); (K.B.); (D.T.)
| | - Daniela Antonova
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bldg. 9, 1113 Sofia, Bulgaria; (V.D.); (D.A.); (L.A.)
| | - Diana Tsobanova
- Department of Technology of Wine and Beer, University of Food Technologies Plovdiv, 26 Maritza blvd., 4002 Plovdiv, Bulgaria; (I.B.); (K.B.); (D.T.)
| | - Valentin Bambalov
- Department of Viticulture, Agricultural University Plovdiv, 12 Mendeleev blvd., 4000 Plovdiv, Bulgaria;
| | - Daniel Cozzolino
- School of Science, RMIT University, GPO Box 2476, Melbourne, VIC 3001, Australia
- Correspondence: ; Tel.: +61-3-99259634
| | - Liudmil Antonov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bldg. 9, 1113 Sofia, Bulgaria; (V.D.); (D.A.); (L.A.)
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Deneva V, Dobrikov G, Crochet A, Nedeltcheva D, Fromm KM, Antonov L. Tautomerism as primary signaling mechanism in metal sensing: the case of amide group. Beilstein J Org Chem 2019; 15:1898-1906. [PMID: 31467611 PMCID: PMC6693416 DOI: 10.3762/bjoc.15.185] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 08/01/2019] [Indexed: 12/16/2022] Open
Abstract
The concept for sensing systems using the tautomerism as elementary signaling process has been further developed by synthesizing a ligand containing 4-(phenyldiazenyl)naphthalene-1-ol as a tautomeric block and an amide group as metal capturing antenna. Although it has been expected that the intramolecular hydrogen bonding (between the tautomeric hydroxy group and the nitrogen atom from the amide group) could stabilize the pure enol form in some solvents, the keto tautomer is also observed. This is a result from the formation of intramolecular associates in some solvents. Strong bathochromic and hyperchromic effects in the visible spectra accompany the 1:1 formation of complexes with some alkaline earth metal ions.
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Affiliation(s)
- Vera Deneva
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Georgi Dobrikov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Aurelien Crochet
- University of Fribourg, Department of Chemistry, Chemin du Musée 9, CH-1700 Fribourg, Switzerland
| | - Daniela Nedeltcheva
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
| | - Katharina M Fromm
- University of Fribourg, Department of Chemistry, Chemin du Musée 9, CH-1700 Fribourg, Switzerland
| | - Liudmil Antonov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia 1113, Bulgaria
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Deneva V, Antonov L. Attaching tweezers like ionophore to a proton crane: theoretical design of new tautomeric sensors. Mol Phys 2019. [DOI: 10.1080/00268976.2018.1562127] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Vera Deneva
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - Liudmil Antonov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria
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Marciniak H, Hristova S, Deneva V, Kamounah FS, Hansen PE, Lochbrunner S, Antonov L. Dynamics of excited state proton transfer in nitro substituted 10-hydroxybenzo[h]quinolines. Phys Chem Chem Phys 2018; 19:26621-26629. [PMID: 28953273 DOI: 10.1039/c7cp04476c] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The ground state tautomerism and excited state intramolecular proton transfer (ESIPT) of 10-hydroxybenzo[h]quinoline (HBQ) and its nitro derivatives, 7-nitrobenzo[h]quinolin-10-ol (2) and 7,9-dinitrobenzo[h]quinolin-10-ol (3), have been studied in acetonitrile using steady state as well as time dependent spectroscopy and quantum-chemical calculations. In addition to the enol form absorbance in the range 360-390 nm, the absorption spectra of 2 and 3 exhibit a red shifted band at ∼450 nm. Chemometric data processing, based on individual band decomposition, allowed us to estimate the position of the ground state enol-keto tautomeric equilibrium (ΔG values of 1.03 and 0.62 kcal mol-1 respectively for 2 and 3). The fluorescence stems from the keto form even if the enol form is optically excited as proven by the shape of the excitation spectra indicating that ESIPT takes place. The Stokes shift of the substituted compounds is substantially lower compared to HBQ, which follows from the fact that the substitution occurs in the formal cyclohexa-2,4-dienone moiety and leads to a decrease of the HOMO level of the keto tautomer. The pump-probe experiments show that in the nitro substituted HBQs 2 and 3 ESIPT occurs with a time constant of 0.89 ps and 0.68 ps, respectively. In both cases a mixture of the enol and proton transfer forms is optically excited. The enol form exhibits then the ESIPT and subsequently both fractions take the same relaxation path. We propose that in 2 and 3 the ESIPT path exhibits a potential energy barrier resulting in an incoherent rate governed process while in HBQ the ESIPT proceeds as a ballistic wavepacket motion along a path without significant barriers. The theoretical calculations (M06-2X/TZVP) confirm the existence of a barrier in the ground and excited states as result of the substitution.
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Affiliation(s)
- H Marciniak
- Institut für Physik, Universität Rostock, Albert-Einstein-Straße 23-24, 18059 Rostock, Germany
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Hristova S, Dobrikov G, Kamounah FS, Kawauchi S, Hansen PE, Deneva V, Nedeltcheva D, Antonov L. 10-Hydroxybenzo[h]quinoline: switching between single- and double-well proton transfer through structural modifications. RSC Adv 2015. [DOI: 10.1039/c5ra20057a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Proton transfer in HBQ and modified compounds was investigated experimentally (steady state absorption and emission spectroscopy, NMR and chemometrics) and theoretically (DFT and TD-DFT M06-2X/TZVP calculations) in ground and excited singlet state.
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Affiliation(s)
- S. Hristova
- Institute of Organic Chemistry with Centre of Phytochemistry
- Bulgarian Academy of Sciences
- 1113 Sofia
- Bulgaria
| | - G. Dobrikov
- Institute of Organic Chemistry with Centre of Phytochemistry
- Bulgarian Academy of Sciences
- 1113 Sofia
- Bulgaria
| | - F. S. Kamounah
- Roskilde University
- Department of Science
- Systems and Models
- Roskilde
- Denmark
| | - S. Kawauchi
- Tokyo Institute of Technology
- Department of Polymer Science
- Tokyo 152
- Japan
| | - P. E. Hansen
- Roskilde University
- Department of Science
- Systems and Models
- Roskilde
- Denmark
| | - V. Deneva
- Institute of Organic Chemistry with Centre of Phytochemistry
- Bulgarian Academy of Sciences
- 1113 Sofia
- Bulgaria
| | - D. Nedeltcheva
- Institute of Organic Chemistry with Centre of Phytochemistry
- Bulgarian Academy of Sciences
- 1113 Sofia
- Bulgaria
| | - L. Antonov
- Institute of Organic Chemistry with Centre of Phytochemistry
- Bulgarian Academy of Sciences
- 1113 Sofia
- Bulgaria
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Ivanova D, Deneva V, Nedeltcheva D, Kamounah FS, Gergov G, Hansen PE, Kawauchi S, Antonov L. Tautomeric transformations of piroxicam in solution: a combined experimental and theoretical study. RSC Adv 2015. [DOI: 10.1039/c5ra03653d] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Piroxicam tautomerism was studied in solution. Enol-amide tautomer is presented mainly as a sandwich type dimer in ethanol and DMSO. The addition of water leads to gradual shift of the equilibrium towards the zwitterionic tautomer.
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Affiliation(s)
- D. Ivanova
- Institute of Organic Chemistry with Centre of Phytochemistry
- Bulgarian Academy of Sciences
- BG-1113 Sofia
- Bulgaria
- Faculty of Pharmacy
| | - V. Deneva
- Institute of Organic Chemistry with Centre of Phytochemistry
- Bulgarian Academy of Sciences
- BG-1113 Sofia
- Bulgaria
| | - D. Nedeltcheva
- Institute of Organic Chemistry with Centre of Phytochemistry
- Bulgarian Academy of Sciences
- BG-1113 Sofia
- Bulgaria
| | - F. S. Kamounah
- Department of Science
- Systems and Models
- Roskilde University
- DK-4000 Roskilde
- Denmark
| | - G. Gergov
- Faculty of Pharmacy
- Medical University of Sofia
- BG-1000 Sofia
- Bulgaria
| | - P. E. Hansen
- Department of Science
- Systems and Models
- Roskilde University
- DK-4000 Roskilde
- Denmark
| | - S. Kawauchi
- Tokyo Institute of Technology
- Department of Organic and Polymeric Materials
- Tokyo 152-8552
- Japan
| | - L. Antonov
- Institute of Organic Chemistry with Centre of Phytochemistry
- Bulgarian Academy of Sciences
- BG-1113 Sofia
- Bulgaria
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Antonov L, Deneva V, Simeonov S, Kurteva V, Crochet A, Fromm KM, Shivachev B, Nikolova R, Savarese M, Adamo C. Controlled Tautomeric Switching in Azonaphthols Tuned by Substituents on the Phenyl Ring. Chemphyschem 2014; 16:649-57. [DOI: 10.1002/cphc.201402691] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Indexed: 11/10/2022]
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Manolova Y, Deneva V, Antonov L, Drakalska E, Momekova D, Lambov N. The effect of the water on the curcumin tautomerism: a quantitative approach. Spectrochim Acta A Mol Biomol Spectrosc 2014; 132:815-820. [PMID: 24973669 DOI: 10.1016/j.saa.2014.05.096] [Citation(s) in RCA: 128] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 05/27/2014] [Accepted: 05/30/2014] [Indexed: 05/28/2023]
Abstract
The tautomerism of curcumin has been investigated in ethanol/water binary mixtures by using UV-Vis spectroscopy and advanced quantum-chemical calculations. The spectral changes were processed by using advanced chemometric procedure, based on resolution of overlapping bands technique. As a result, molar fractions of the tautomers and their individual spectra have been estimated. It has been shown that in ethanol the enol-keto tautomer only is presented. The addition of water leads to appearance of a new spectral band, which was assigned to the diketo tautomeric form. The results show that in 90% water/10% ethanol the diketo form is dominating. The observed shift in the equilibrium is explained by the quantum chemical calculations, which show that water molecules stabilize diketo tautomer through formation of stable complexes. To our best knowledge we report for the first time quantitative data for the tautomerism of curcumin and the effect of the water.
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Affiliation(s)
- Yana Manolova
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bldg. 9, 1113 Sofia, Bulgaria
| | - Vera Deneva
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bldg. 9, 1113 Sofia, Bulgaria
| | - Liudmil Antonov
- Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bldg. 9, 1113 Sofia, Bulgaria.
| | - Elena Drakalska
- Faculty of Pharmacy, Medical University - Sofia, 2 Dunav Str., 1000 Sofia, Bulgaria
| | - Denitsa Momekova
- Faculty of Pharmacy, Medical University - Sofia, 2 Dunav Str., 1000 Sofia, Bulgaria
| | - Nikolay Lambov
- Faculty of Pharmacy, Medical University - Sofia, 2 Dunav Str., 1000 Sofia, Bulgaria
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Deneva V, Manolova Y, Lubenov L, Kuteva V, Kamounah F, Nikolova R, Shivachev B, Antonov L. Controlled shift in the tautomeric equilibrium of 4-((phenylimino)methyl)naphthalen-1-ol. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2012.11.055] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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17
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Antonov L, Deneva V, Kurteva V, Nedeltcheva D, Crochet A, Fromm KM. Controlled tautomerism – switching caused by an “underground” anionic effect. RSC Adv 2013. [DOI: 10.1039/c3ra45326j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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Antonov L, Deneva V, Simeonov S, Kurteva V, Nedeltcheva D, Wirz J. Exploiting Tautomerism for Switching and Signaling. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200903301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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19
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Antonov L, Deneva V, Simeonov S, Kurteva V, Nedeltcheva D, Wirz J. Exploiting Tautomerism for Switching and Signaling. Angew Chem Int Ed Engl 2009; 48:7875-8. [DOI: 10.1002/anie.200903301] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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